1. Field of the Disclosure
The present disclosure relates generally to communication systems, and more particularly to a load balancing reverse power supply that estimates communication line power losses.
2. Description of the Related Art
Various communication standards, such as digital subscriber line (xDSL), very-high-bit-rate digital subscriber line 2 (VDSL2), G.hn, and G.fast, have been proposed or developed to provide high-speed data transmission from the service provider (e.g., a central office) to a customer premise over the existing twisted-pair copper wiring conventionally used for telephone service. Such technologies leverage modem technology to increase the data transfer bandwidth of the twisted-pair copper wiring. Typically, modems are provided on the ends of the subscriber line copper wiring to communicate between the central office and the customer premise. The manner in which the two modems communicate is established by the particular standard governing the communication. Because the existing telephone wire is used, the data signals are typically transferred out-of band with the voice band signals. Because different frequencies are used for the voice band and the data band, voice and data information can be concurrently transferred over the twisted-pair copper line.
Service providers have increased data bandwidth by installing fiber optic cabling between the central office and a distribution point (DP) closer to the customers. A particular DP may interface with a bundle of twisted pairs to service a relatively small number of customer premise connections. This approach shortens the length of the copper pair between the CO interface at the DP and the customer, thereby allowing increased data rates.
One difficulty arising from an optical connection between the central office and the DP lies in the ability to provide a source of power for the DP. Due to the remoteness of the DP with respect to the central office, a local power supply is often unavailable or expensive to install. Power over Ethernet (PoE) devices have been developed, which in general terms, provide for power sourcing equipment (PSE) which is arranged to detect, optionally classify, and ultimately, provide power over data communication cabling to a powered device (PD) without interfering with data communication. PoE may be adapted to allow the customer premise equipment (CPE) to use its local power supply to act as a PSE so as to generate a DC voltage that may be superimposed with the data and voice signals being communicated over the twisted pair connection to allow the DP to extract power for its own use as a PD. A power supply in the DP combines power contributions from multiple CPE units to power a main distribution unit (MDU) that handles the voice and data communication. This arrangement is referred to as a reverse power system, where the CPEs are the power sourcing equipment (PSE) and the DP is the PD.
The power supply may attempt to balance the power delivered by the CPE units, so that each CPE is delivering an equal amount of power. However, since the length of the twisted pair connection between the DP and the various CPEs may differ, balancing the power just based on power delivered by PDs may not be “fair”, as CPEs with longer communication lines may then actually output more total power than those with shorter communication lines due to communication line power losses.